The present invention relates to a multilayered integrated circuit chip.
Conventional integrated circuit chips are constructed of upper and lower layers of parallel conductors between which insulative layers of silicon dioxide and silica are interposed. The conductors of the underlying layer extend in a direction normal to the length of the conductors of the upper layer and are separated at intervals according to predetermined requirements. The insulative intermediate layers are deposited over the conductors of the underlying layer so that the spaces between adjacent lower-layer conductors are completely filled by insulating material. As viewed from ends of the underlying conductors, the insulators describe an undulating curve having troughs corresponding to the spaces where underlying conductors are absent and crests corresponding to the spaces where they are present. Since the upper conductors extend in a direction normal to the length of the underlying conductors, they follow the undulating curve of the insulators, producing thinner portions corresponding to the troughs of the curve and thicker portions corresponding to the crests. The ratio of maximum film thickness to minimum film thickness, or "step coverage", of the overlying conductors is reduced to a level not satisfactory from the viewpoint of what is called the "electromigration" of the overlying conductors.